1. Technical Field
The present invention relates generally to the field of wireless communication systems and more particularly to an improved system and method of operation for managing the contents of a visitor location register contained within such a wireless communication system to achieve improved network capacity.
2. Related Art
Cellular based wireless communication systems are well known in the art. In the operation and management of a cellular communication system, a large number of mobile terminals, typically being battery powered, operate wirelessly throughout the system. Such systems typically include a number of mobile switching centers ("MSC") that provide high level management of a relatively large service area. As well as providing management functions, each MSC typically also provides an interface between the wireless communication system and the public switched telephone network ("PSTN"). In most applications, a plurality of base system controllers ("BSC") connect to each MSC and a plurality of base transceiver stations ("BTS") connect to each BSC, each BTS establishing a respective cell and facilitating wireless communications within the respective cell.
In a wireless communication system, subscriber information corresponding to mobile terminals is required for operation. Subscriber information for a particular mobile terminal is stored in a centralized database, commonly referred to as a home location register ("HLR"). Such subscriber information is established upon activation of the mobile terminal and resides within the HLR until removed upon deactivation. When a mobile terminal visits an area served by a particular MSC, the MSC retrieves respective subscriber information from the HLR and stores the subscriber information in what is referred to as a visitor location register ("VLR"). Subsequently, the MSC uses the subscriber information stored in the VLR to route calls to and from the mobile terminal as well as to validate calls initiated from within corresponding cells.
Prior art VLR management techniques typically retained retrieved subscriber information in the VLR only for so long as the respective mobile terminal remained active within the corresponding cells. However, once the mobile terminal ceased activity within the respective cells, the subscriber information stored within the VLR for the particular mobile terminal was deleted. Since the processing required to retrieve of records from the HLR was great and system resources were consumed in the retrieval and storage of the subscriber information in the VLR, network capacity was limited.
Thus, there is a need in the art for an improved system and technique for managing VLRs that not only more efficiently stores subscriber information within the VLR but that manages subscriber information within the VLR to minimize downloads from the HLR that increases the network capacity.